What is the atomic weight of a penny?

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

The air that we breath is made mostly of which gaseous molecule